The fields of application of various power converters have been developed with increasing practical applications of variable voltage variable frequency inverter units.
As regards the power converters, for example, the application and development of technology of step-up/down converters have been actively promoted in recent years. Meanwhile, wide band gap semiconductor devices including silicon carbide has also been actively developed. Some of such new devices have high voltage withstanding characteristics and small current capacities (allowable current effective values). These devices have been put into practical use mainly as rectifiers (refer to Patent Literature 1, for example).